Many newly emerging diseases are caused by zoonotic agents with wildlife reservoirs or have resulted from Iarge-scale ecological changes that increase human exposure to insect vectors as well as to animal and environmental sources of disease. Approximately 80% of the infectious agents that cause disease in humans are shared with various animal hosts. Veterinarians are good candidates to study these emerging diseases, but training programs aimed at disease pathogenesis and epidemiology specifically tailored to wildlife diseases are lacking. The proposed training will provide a multidisciplinary program in infectious diseases, pathogenesis, molecular diagnostic methodologies, pathology, fundamentals of laboratory animal medicine, epidemiology and disease modeling. The model system chosen for the research component, upper respiratory tract disease (URTD) in gopher tortoises, is an excellent example of chronic disease in a nontraditional animal host. URTD represents an intriguing model to study establishment, transmission, maintenance, and consequences of chronic infection within a population with a life history that parallels humans. The proposed study will address the following hypotheses: (1) URTD is caused by a cluster of closely related mycoplasmal species. The specific species involved may vary within tortoise populations, and these species may differ regionally and, (2) Mycoplasmas vary in virulence, and the specific mycoplasma present in a given population will influence the transmission, clinical course and severity of URTD. The hypotheses will be addressed with the following specific aims: (1) To characterize the molecular epidemiology of mycoplasmal species and selected strains obtained from different tortoise populations; (2) To characterize the virulence of mycoplasmal species and selected strains obtained from different tortoise populations; (3) To develop a multi-plex Luminex assay for quantitation of antibodies to mycoplasmal species from tortoises; and (4) To identify genes associated with virulent and avirulent mycoplasmal species and selected strains. The study of a chronic respiratory infection in a natural population will provide a framework for the development of predictive and casual models that may provide valuable insights into the mechanisms by which chronic infections are maintained and transmitted on a population basis.